Session 3: The Nose and Paranasal Sinuses; The External and Middle Ear Flashcards
What is the external nose composed of?
Partly of bone and partly of hyaline cartilage, with the nasal bones meeting in the midline superiorly.
Where do the nasal bones meet?
Superiorly in the midline
What forms the lower boundary of the external nose?
The meeting of the two maxillae
What forms the lateral boundary of the external nasal aperture (naris)?
Fibrofatty tissue posteriorly and major alar cartilage anteriorly.
What forms the medial boundary of the aperture of the external nose below the nasal septum?
The major alar cartilages turning inwards
What is the vestibule of the nose?
The short distance into the nose into which the hairy skin of the external nose extends
What divides the nasal cavity into right and left halves?
Nasal septum
What forms the medial wall of each nasal cavity?
Nasal septum
What is attached to the nasal septum superiorly?
Perpendicular plate of the ethmoid
What is attached to the nasal septum posteriorly?
Vomer
What is attached to the nasal septum anteriorly?
Major alar cartilage
What forms the roof of the nasal cavity?
Anteriorly - Nasal bones
Middle - Cribiform plate of ethmoid
Posteriorly - Inferior surface of the body of the sphenoid
What passes through the cribiform plate of the ethmoid?
Olfactory nerves to reach the olfactory bulb
What forms the floor of the nasal cavity?
Anteriorly - Palatine processes of maxillae
Posteriorly - Horizontal plates of palatine bones
What forms the lateral walls of the nasal cavity?
Maxillae + 3 conchae
What bones are the superior, middle and inferior conchae part of?
Superior + middle = part of ethmoid
Inferior = separate bone
Describe the conchae.
Large, medially-directed bony elements covered by highly vascular mucous membranes. On the lateral walls of the nasal cavity.
What is the action of the conchae?
To heat and humidify air that passes them during breathing
Where are the meatuses in relation to the conchae?
Beneath each shelf like conchae
What opens into the meatuses?
Paranasal sinuses
Which paranasal sinus opens into the superior meatus?
Posterior ethmoidal
Which paranasal sinuses open into the middle meatus?
Maxillary, frontal, anterior ethmoidal, middle ethmoidal
What opens into the inferior meatus?
Nasolacrimal duct
Where does the sphenoidal sinus open?
Sphenoidal recess posterior to the superior conchae/meatus
Where does the Eustachian tube open?
The lateral wall of the nasal cavity, posterior to the inferior conchae/meatus.
Which arteries supply the nasal cavity? (4)
FROM ECA: - sphenopalatine artery (maxillary) - ascending branch greater palatine (maxillary) - labial (facial artery) FROM ICA: - anterior ethmoidal (opthalmic)
Which veins does the venous blood drain into?
Facial, opthalmic and sphenopalatine veins.
What do the sphenopalatine veins form?
Pterygoid plexus of veins in the infratemporal fossa
Where is the olfactory mucous membrane located? What is it responsible for?
Roof and adjacent parts of medial and lateral walls, smell
Which epithelium covers the olfactory mucous membrane?
Columnar epithelium
Which epithelium covers the vestibule?
Stratified squamous epithelium
Which epithelium covers the nasal cavity? (not vestibule or olfactory mucous membrane)
Respiratory epithelium
What is general sensation in the nasal cavity mediated by?
Branches of Va and Vb
What is the parasympathetic secretomotor supply to the nasal cavity?
Greater petrosal (VII) –> pterygopalatine ganglion –> branches of Vb
Which epithelium lines the paranasal sinuses?
Ciliated mucous columnar epithelium
How are the ciliary currents directed?
Spirally towards the opening of the sinuses
Where does the frontal sinus lie?
Above the orbit
Where does the frontal sinus enter the nasal cavity?
Anterior end of middle meatus
Describe the maxillary sinus. Where does it lie?
Large, occupies most of the maxilla
Lies lateral to the nasal cavity, above the upper molar teeth. Its floor extends to a lower level than the floor of the nasal cavity.
Describe the opening of the maxillary sinus.
It is above the level of the floor of the maxillary sinus. It drains into the middle meatus